Just because there are a huge amount of fixes/changes/updates in the latest development branch, here's a list of changes that went into the latest development commit (ea02cd83f268106b6e6ca5bfb2b561d16a94c7d3 @ May 25/2014). I'll also break into some futher detail on some items that might require more clarification (ie. search order provider).

IMPROVEMENTS (mixed with FIXES)
IMP: Ability to now specify search provider order (regardless of torrents or nzb) within the config.ini,
IMP: (#667) Changed the database module to try to accommodate database locking errors and lowering the amount of actual write transactions that were committed
IMP: Changed sabnzbd directory to post-processing, and included subdirs for sabnzbd & nzbget ComicRN scripts
IMP: NZBGet Post-Processing ComicRN.py script (updated for use with nzbget v11.0+)added & updated in post-processing/nzbget directory (thnx ministoat)
IMP: Added universal date-time conversion to allow for non-english based dates to be properly compared when checking search results against publication dates
IMP: Exception/traceback handling are now logged by default to the mylar.log file
IMP: (#689) Minimum # of seeders added (will work with KAT)
IMP: (#680) Added Boxcar 2 IO Notifications
IMP: Added PushBullet Notifications
IMP: Cleaned up some notification messages so it's not so cluttered
IMP: Added Clickable series link in History tab
IMP: Added Post-Processed as a status to History tab to show manually post-processed items instead of everything being lumped as 'Downloaded'
IMP: Removed log level dropdown from Logs page & added 'ThreadName' as a column
IMP: Added Force Check Availability & View Future Pull-list to Upcoming sub-tabs
IMP: Added '--safe' option to startup options which will redirect directly to Manage Comics screen incase things are broken
IMP: Added Scheduler (from sickbeard) to allow for threadnaming and better scheduling
IMP: Filenames in the format of '$Series ($Year) $Issue' will now get scanned in
IMP: During manual post-processing will now stop looking through remainder of files for further matches upon a successful match
IMP: A Refresh/Weeklypull series check will now just scan in issue data, instead of series info, etc
IMP: Removed some legacy GCD code that is no longer in use
IMP: Improved future pull-list detection and increased retension (now ~5 months)
IMP: Will now mark new issues as Wanted on a Refresh Series if autowant upcoming is enabled (was reverting to a status of None previously)
IMP: Cannot change status to Downloaded if current status is Skipped or Wanted
IMP: future_check will check upcoming future issues (future pull-list) that have no series data yet (ie. #1's) and auto-add them to watchlist when the data is available and auto-want accordingly
IMP: (#706) Downloading issues to local machine (via comicdetails screen) with special characters in filename now will work
IMP: improved comparison checks during weekly pull list and improved speed abit since only refreshing issue data now instead of entire series

SPECIFIC FIXES:
FIX: If Issue Location was None, and status was Downloaded would cause error in GUI and break series
FIX: Unable to grab torrents from KAT due to content-encoding detection failing
FIX: Added proper month conversions for manual post-processing when doing comparitive issue analysis for matches
FIX: (#613) Allow for negative issue numbers in post-processing when renaming and issue padding is enabled
FIX: File Permissions on post-processing would stop post-processing if couldn't change, now will just log the error and continue
FIX: Annuals will now get proper notification (prior was leaving out the word 'annual' from notification/logs)
FIX: (#704) UnSkipped will now work (X in options column on comic details page)